(m) the potential uses of stem cells in research and medicine.

The idea

Stem cells are undifferentiated cells able to divide and differentiate into specialised cell types. Their potential uses fall into research and medicine. In research, pluripotent and multipotent stem cells provide models for studying development, gene expression and disease, and can be used to test drugs and toxicity. In medicine, stem cells may be used to replace damaged or lost tissues, for example bone marrow transplants to restore blood cells, or potential therapies for repairing tissue such as nerve or heart tissue. A useful method is to separate each use into research or medicine, then state the property of stem cells that makes it possible, such as self-renewal or potency. Recognise that many medical applications remain experimental and raise ethical issues, so the word potential matters.

What earns the marks

• Stem cells are undifferentiated cells that can divide and differentiate into specialised cell types.
• In research, stem cells can be used to study development, gene expression and disease, and to test drugs or toxicity.
• In medicine, stem cells have potential to replace damaged or lost tissues, such as in bone marrow transplants.
• Potential therapies include repairing tissues such as nerve or heart tissue, though many remain experimental.
• The use of stem cells raises ethical issues, which is why the statement refers to potential uses.

Common mistakes and how to put them right

• Treating all stem cell therapies as established.

  Put it right by noting many medical uses are still potential or experimental.

• Confusing research uses with medical treatments.

  Put it right by separating studying and testing from replacing damaged tissue.

• Ignoring the ethical dimension.

  Put it right by acknowledging ethical issues alongside the benefits.

• Assuming stem cells are already specialised.

  Put it right by stating they are undifferentiated and can differentiate.

Exam tips

• Classify each option as a research use or a medical use before deciding.
• Reject options that overstate certainty; the statement refers to potential uses.
• Link each use to a stem cell property such as self-renewal or potency.
• Consider ethical issues when an option presents stem cell use as entirely without controversy.